Direct silanol analysis of tribological surfaces using synchrotron radiation

A new direct detection technique for silanol is needed for tribological materials containing silicon. We focused on near-edge X-ray absorption fine structure (NEXAFS), which uses synchrotron radiation as a method for directly detecting silanol. Model samples were prepared, and their spectra were obtained by NEXAFS. The Si and the O K-edge spectra of silanol exhibited peaks at approximately 1843 eV and 535 eV, respectively. Then the surfaces of silicon-containing diamond-like carbon (DLC-Si) films were measured. The amount of silanol on high-silicon-doped DLC, which had a low friction coefficient, was found to be greater than that on low-silicon-doped DLC. In this research, we demonstrated that the silanol on the surface of DLC-Si films can be directly detected and identified by NEXAFS. •A direct silanol detection method is developed for tribological surfaces using NEXAFS via synchrotron radiation.•Si K-edge and O K-edge NEXAFS spectra of silanol exhibited peaks at approximately 1843 eV and 535 eV, respectively.•Silanol on the friction surfaces of DLC-Si films can be directly detected and identified by NEXAFS.•The technique greatly helps to understand the mechanism of silicon-assisted interfacial phenomena of tribological properties.